Production of alkenyl thiophenes



Ktadiene-IA, l-methylcyclopentadiene-1,

Patented Nov. 4, 1952 ama s? FJEQPUQTIQN s art? Herman ines and- Bruno Kvetinskas, Ghi

111., assignorstoUniversal OiI 'PrBHu 't's Qo ago, Ill., acorpo'i ation of 'llela war .2 Qlairns, (01. 260-829) This invention. relates .to new compositions of matter consisting. ofnovel chemical compounds. It. is more. specifically concerned with .thiophenes in which at least one .otthe nuclearmhydrogen atoms has. been replaced by. a tertiary. alkenyl group. This application is a conti-niiation-inpart'of our earlier applicationserial No. 651,435,

filed March 1, 1946.'

It is an object of this invention to provide thiophenes inwhich at least one of the nuclear hydrogen atoms has been replaced by. an'ole'finic tertiary hydrocarbon radical. are usefulas chemical intermediates. for the syn,-

S'uch. compounds thesis of medicinals, 'bacter'icides, insecticides,

and other organic compounds. and in -the preparation of sulfur-containing plastics. Alkenyl thi'ophenes; inwhich the carbon atom of the side. chain that is attached to the thiophene nucleus is joined to threeother carbon atoms inthe side chain, are. more readily polymerized than otheii typsof alkenyl vthiophen'es and producemoi e highly branched polymers.

In one embodiment. my invention relates to a compound of th'e following formula:

E f s k a. REAR in which at leastone of the groups B}, R R and B i a d qee ie pat ma ner are selected from the group consisting arrearsg en'i alkyl, cycloalkyl," allge nyl, "aryl, alliary-l, aralkyl, ahd naphthylr adieals. i

Substances :Whichi catalyze the alkenylation at a thiophene with aftertiary 'diolefin include stannici chloride.' This inetal 'halide' 'catalystis preferably used in a substantially aiuq germane be used as "such 01 Hope substantially "inert carriers, such. s1" crIus quart porcelain, fire brick'fand siriiilai gianular materials. In some cases it is advantageous to add a hydrogen halide, such as hydrogen R3, R and 13A is a tertiary alkenyl radical and J the other substituents are selected from the group'consistingof hydrogen, alkyl, cyclo-alkyl,

alkenyl, aryl, alkaryl, aralkyl, and naphthyl rad icals.

r The compounds of this invention may be pro duped by alkenylating a thiophene containing:

atfleastone substitutable position an aliphatic or cyclic diolefin in which at least one of the double bonds is attached to a t rtiary carbon atom- E mples o su h diolefins e:

h men: and 2- methylcyclohexadiene-F.,3. In general, the conjugated diolefins are more active, than the isoprene. 2,.-methylpentadie'ne -1,3, ZQ-inet conjugated diolefins. Diole fins such asig d-dimethyIheptadiene-LS, in which both of the dour.

ble bonds are attached to tertiary carbon atoms, can be used, but they tend to react with two molecules of thiophene to yield dithienyl alkanes.

The use of the term tertiary alkenyl radical? in this specification and the appended claims is meant to cover monooleiinic tertia y aliphatic as a fixed bed within a reactor and the read;

tants continuously passed through the bed at alkenylation conditions. The alkenylate in the effluent is recovered and the unreacted hydrocarbons and unconverted thiophene may be separated and recycled to the alkenylation step for further reaction.

The process of this invention may be conducted at temperatures within the range of from about -20 C. to about 175 C. The preferred temperature will depend to some extent upon the particular thiophene and diolefin charged to the process and upon the activity of the particular alkenylation catalyst employed. The pressure should be such that substantially all of the reactants are in the liquid phase. In general these pressures ,will lie in the'range of from 1 atmosphere to about 100 atmospheres. When a, liquid catalyst is used, the contact time may be in the range of from about three minutes to about three hours. If a solid catalyst is used in a fixed bed, the liquid hourly space velocity, de-.

fined as the volume of total feed to the alkenylation zone per hour divided by the superficial volume of catalyst in said zone, should be in the range of from about 0.1 to about 10. A molecular excess of the thiophene over the diolefin in the reaction zone promotes alkenylation and suppresses side reactions.

The following examples are given to illustrate our invention but they are not introduced with the intention ofunduly limiting the generally broadscope of said invention.

Example I Seventy-six grams of thiophene and 15 grams of stannic chloride were placed in a 250 ml. alkylation flask. To this was added over a period of 2 hours at room temperature 20.5 grams of 2-methylpentadiene-1,3. The temperature was then raised to 50 C. After this the product was cooled and the catalyst phase removed. The organic layer weighing 92-grams was washed. dried, and distilled. Forty-eight grams of thiophene was recovered. Analysis showed that 73 mol percent of the methylpentadiene reacted to form 2- (1',1-dimethyl-2'-butenyl) -thiophene and 20% of the diene yielded dihexenyl thiophene. The monoalkenylthiophenehad a boiling point of 79 C. at 5.5 mm. pressure and a n of 1.5175.

Example II Seventy-six grams of thiophene was reacted with 17 grams of isoprene in the presence of 15 grams of stannic chloride, in the manner described under Example I. Upon completion of the experiment, the upper layer, which weighed 84- grams, was washed, dried, and distilled. Forty-seven grams of thiophene was recovered. It was shown that on the basis of isoprene reacted, the yield of 2-(1',1'-dimethyl-'propenyl)f thiophenewas 71% and that the yield of dipentenyl thiophene was 11%. The dimethyl propenylthiophene had a boiling point of 89 C. at'15 mm. pressure, a n of 1.5269, and a density of 0.9788 at 20 C.

Example III Seventy grams of thiophene is reacted with 25 grams of 2-methylcyclohexadiene-1,3 in the presence of a stannic chloride catalyst in the manner described under Example I. The compound 2- (1'--methyl-2 -cyclohexenyl) thiophene is iden-' tified in the product. 1

Example IV 50.4 grams of thiophene and 22.3 grams of stannic chloride were mixed in a glass reactor provided with a motor driven stirrer and isobutylene was introduced to the stirred mixture until a total of 17.5 grams'of theolefin had been introduced. At the beginning of the reaction,

the temperature was 20 C. but due to the heat of reaction this increased to 50 C. when all of the isobutylene had been added at the end of 1.25 hours. The reaction product was then washed with water, dried, and distilled. After removing the excess of unconverted thiophene, a mixture of tertiary-butylthiophenes remained. Of the isobutylene charged to the reaction, 18.5% was converted into monotertiary-butylthiophene and 50% into ditertiary-butylthiophene. In addition, 10 grams of a brown solid remained as a distillation residue. The monotertiary-butylthiophene boiled at'61.3 C. at a pressure of 21 mm. of mercury and had a refractive index, n of 1.4976, and a density of 0.9501 at 20 C.; the ditertiary-butylthiophene boiled from 101 to 107 C. at 17 mm. pressure and had a refractive index, 11. of 1.4930.

The monotertiary-butylthiophene was reacted with isoprene and 2-methylpentadiene-1,3 according to the procedure described in the preceding examples. In both experiments 2-alkenyl-5- alkylthiophenes were identified in the product. Isopropyl thiophene, secondary butylthiophene, and cyclohexylthiophene were alkenylated in a similar manner with similar results.

We claim as our invention:

1. A process for producing an alkenyl thiophene which comprises catalytically reacting a thiophene having a nuclear hydrogen atom with a diolefin containing one tertiary double bond and one non-tertiary double bond.

2. A process for producing an alkenyl thiophene which comprises reacting a thiophene having a nuclear hydrogen atom with a diolefin containing one tertiary double bond and one non-tertiary double bond at a temperature of from about 20 C. to about C. in the presence of stannic chloride.

HERMAN PINES. BRUNO KVETINSKAS.

REFERENCES CITED The followingreferences are of record in the file of this patent: I

V UNITED STATES PATENTS Number Name Date 2,141,611v Malishev Dec. 27, 1938 2,490,270 Johnson Dec. 6, 1949 OTHER REFERENCES 

1. A PROCESS FOR PRODUCING AN ALKENYL THIOPHENE WHICH COMPRISES CATALYTICALLY REACTING A THIOPHENE HAVING A NUCLEAR HYDROGEN ATOM WITH A DIOLEFIN CONTAINING ONE TERTIARY DOUBLE BOND AND ONE NON-TERTIARY DOUBLE BOND. 